I have an application which contains two .exe's (one service, one agent) and i am making them into a single MSI package for my windows system using WIX(windows installer xml) so that it will start as windows service.
Now I want to make this for MAC OS. What are prerequisites I should consider?
MSI packages are only supported on Microsoft platforms, so you won't be able to use this technology on Mac OS systems. Also EXE files can't be executed on Mac, except you are using an emulator like Winebottler for example.
Once you've compiled your applications for Mac OS, you could use Iceberg (http://s.sudre.free.fr/Software/Iceberg.html) in order to create installation packages for Mac OS.
Sometimes it's easier to capture an installation by comparing snapshots. In this case InstallEase might be helpful. (http://www.absolute.com/products/endpoint-management/InstallEase).
What you need to do is: Create the initial snapshot, install your applications and configure them the way you need. Afterwards create a second snapshot. The diff of these two snapshots basically is your package.